Silicone Polydimethylsiloxane

Silicones. Polydimethylsiloxanes, polydiphenylsiloxanes, and polymethylphenylsHoxanes are generally called siUcones (see Silicon COMPOUNDS, silicones). With a repeating unit of alternating siUcon-oxygen, the siloxane chemical backbone stmcture, siUcone possesses excellent thermal stabiUty and flexibility that are superior to most other materials. Polydimethjisiloxane provides a very low glass-transition temperature T material but is suitable for use... 

Membranes can be classified as porous and nonporous based on the structure or as flat sheet and hollow fiber based on the geometry. Membranes used in pervaporation and gas permeation are typically hydrophobic, nonporous silicone (polydimethylsiloxane or PDMS) membranes. Organic compounds in water dissolve into the membrane and get extracted, while the aqueous matrix passes unextracted. The use of mircoporous membrane (made of polypropylene, cellulose, or Teflon) in pervaporation has also been reported, but this membrane allows the passage of large quantities of water. Usually, water has to be removed before it enters the analytical instrument, except when it is used as a chemical ionization reagent gas in MS [50], It has been reported that permeation is faster across a composite membrane, which has a thin (e.g., 1 pm) siloxane film deposited on a layer of microporous polypropylene [61],... 

Silicone Polydimethylsiloxane Works by producing a char surface Polyolefins, polyolefin blends, EVA, polycarbonate, polyurethane Dow Corning, GE Silicones... 

Synonyms dimethyl silicone polydimethylsiloxane Dimethyl Sulfide... 

Silicones (polydimethylsiloxanes) High-Temperature hydrocarbons RTEmp fluid... 

Physical and chemical properties of silicone (polydimethylsiloxane), Dow Corning, http //www.dowcorning.com/content/discover/discoverchem/properties.aspx e=Physical +%26+Chemical+Properties, 2000-2014. 

Chem. Descrip. Nonsilicone and silicone (polydimethylsiloxane) emulsion Uses Defoamer/antifoam for aq. industrial systems, wastewater, effluent, high-... 

Silicone (polydimethylsiloxane) was selected as the binder due to its mechanical flexibility and thermal stability over a broad temperature range (-79 to 204 °C). Silicone maintains relatively high strain to failure and durability at low temperatures and is utilized in automotive applications due to its high temperature performance. Furthermore, silicone decomposes at a higher temperature than most other flexible polymers and absorbs a considerable amount of energy in the process. Silicone has... 

Silicone Fluids. Sihcone fluids are used in a wide variety of appHcations, including damping fluids, dielectric fluids, poHshes, cosmetic and personal care additives, textile finishes, hydraiflic fluids, paint additives, and heat-transfer oils. Polydimethylsiloxane oils are manufactured by the equihbrium polymerisation of cycHc or linear dimethyl silicone precursors. Trifunctional organosilane end groups, typically trimethylsilyl (M), are used, and the ratio of end group to chain units (D), ie, M/D, controls the ultimate average molecular weight and viscosity (112). Low viscosity fluids,... 

Silicone Heat-Cured Rubber. Sihcone elastomers are made by vulcanising high molecular weight (>5 x 10 mol wt) linear polydimethylsiloxane polymer, often called gum. Fillers are used in these formulations to increase strength through reinforcement. Extending fillers and various additives, eg, antioxidants, adhesion promoters, and pigments, can be used to obtain certain properties (59,357,364). 

It is generally considered in this notation that methyl groups are attached to silicon atoms. This nomenclature allows structures like trimethylsiloxy-endblocked-polydimethylsiloxane (TMS-eb-PDMS) to be simply represented as MD M (Scheme 2). 

Polydimethylsiloxane (PDMS) dimethicone cyclomethicone cetyl dimethicone cyclopentasiloxane silicone oil... 

Flexible foams with oxygen index values of 40-53 were also prepared by the same authors from blends of copolymer IV and a silicone elastomer, (a phenyl vinyl polydimethylsiloxane) [592]. 

If a material other than a hydrocarbon is used as the base material of an ointment-like system, the ointment bears the name of its principal ingredient. There are silicone ointments that contain polydimethylsiloxane oil in large proportion. These reportedly act as excellent water barriers and superior emollients. Some are actually used to protect skin from the undesirable effects of long immersion in water. 

Recent work has focused on a variety of thermoplastic elastomers and modified thermoplastic polyimides based on the aminopropyl end functionality present in suitably equilibrated polydimethylsiloxanes. Characteristic of these are the urea linked materials described in references 22-25. The chemistry is summarized in Scheme 7. A characteristic stress-strain curve and dynamic mechanical behavior for the urea linked systems in provided in Figures 3 and 4. It was of interest to note that the ultimate properties of the soluble, processible, urea linked copolymers were equivalent to some of the best silica reinforced, chemically crosslinked, silicone rubber... 

Two major classes of hydrophobic chemical substances can be applied to glass in ultrathin layers to inhibit surface wetting. Siloxanes or polysiloxanes or silicones are polymers with a backbone of alternating silicon and oxygen atoms. These macromolecules are quite chemically inert, show resistance to water, and exhibit stability at high and low temperatures. The most common siloxane polymer, polydimethylsiloxane, is composed of the monomeric (i.e., repeating) unit illustrated in Fig. 7.5.1. 

Current polymeric entubulization repair methods for peripheral nerve regeneration use various nondegradable and biodegradable materials. The most common nondegradable material investigated has been silicone rubber. Medical grade silicone rubber, polydimethylsiloxane, maintains its shape and can be filled with neurotrophic factors or extracellular... 

---